136-456: Batesian mimicry is a form of mimicry where a harmless species has evolved to imitate the warning signals of a harmful species directed at a predator of them both. It is named after the English naturalist Henry Walter Bates , who worked on butterflies in the rainforests of Brazil. Batesian mimicry is the most commonly known and widely studied of mimicry complexes, such that the word mimicry
272-484: A decorator crab decorates its back with seaweed, sponges and stones. In variable protective resemblance, an animal such as a chameleon , flatfish, squid or octopus changes its skin pattern and colour using special chromatophore cells to resemble whatever background it is currently resting on (as well as for signalling ). The main mechanisms to create the resemblances described by Poulton – whether in nature or in military applications – are crypsis , blending into
408-419: A flower mantis resembles a particular kind of flower, such as an orchid . In general aggressive resemblance, the predator or parasite blends in with the background, for example when a leopard is hard to see in long grass. For adventitious protection, an animal uses materials such as twigs, sand, or pieces of shell to conceal its outline, for example when a caddis fly larva builds a decorated case, or when
544-458: A supergene for the development of butterfly color patterns. The model is supported by computational simulations of population genetics . The Batesian mimicry in Papilio polytes is controlled by the doublesex gene. Some mimicry is imperfect. Natural selection drives mimicry only far enough to deceive predators. For example, when predators avoid a mimic that imperfectly resembles a coral snake,
680-547: A wasp , is harmful, and is avoided by the dupe, such as an insect-eating bird. Birds hunt by sight, so the mimicry in that case is visual, but in other cases mimicry may make use of any of the senses. Most types of mimicry, including Batesian, are deceptive, as the mimics are not harmful, but Müllerian mimicry , where different harmful species resemble each other, is honest , as when species of wasps and of bees all have genuinely aposematic warning coloration. More complex types may be bipolar, involving only two species, such as when
816-420: A caterpillar resembles a twig or a bird dropping. In general protective resemblance, now called crypsis , the animal's texture blends with the background, for example when a moth's colour and pattern blend in with tree bark. Aggressive resemblance is used by predators or parasites . In special aggressive resemblance, the animal looks like something else, luring the prey or host to approach, for example when
952-418: A complex cluster of linked genes that cause large changes in morphology. The second step consists of selections on genes with smaller phenotypic effects, creating an increasingly close resemblance. This model is supported by empirical evidence that suggests that a few single point mutations cause large phenotypic effects, while numerous others produce smaller effects. Some regulatory elements collaborate to form
1088-607: A decade. Bates's field research included collecting almost a hundred species of butterflies from the families Ithomiinae and Heliconiinae , as well as thousands of other insects specimens. In sorting these butterflies into similar groups based on appearance, inconsistencies began to arise. Some appeared superficially similar to others, so much so that even Bates could not tell some species apart based only on wing appearance. However, closer examination of less obvious morphological characters seemed to show that they were not even closely related. Shortly after his return to England, he read
1224-430: A genus of flatworm , matures in the digestive system of songbirds , their eggs then passing out of the bird in the faeces . They are then taken up by Succinea , a terrestrial snail. The eggs develop in this intermediate host , and must then find a suitable bird to mature in. Since the host birds do not eat snails, the sporocyst has another strategy to reach its host's intestine. They are brightly coloured and move in
1360-591: A journal article on mimicry in German in 1878, followed in 1879 by a paper to the Entomological Society of London (translated and presented by Ralph Meldola). He described a situation where different species were each unpalatable to predators, and shared similar, genuine, warning signals. Bates found it hard to explain why this should be so, asking why they should need to mimic each other if both were harmful and could warn off predators on their own. Müller put forward
1496-440: A leaf-mimicking plant, the chameleon vine , employs Batesian mimicry by adapting its leaf shape and colour to match that of its host to deter herbivores from eating its edible leaves. Another analogous case within a single species has been termed Browerian mimicry (after Lincoln P. Brower and Jane Van Zandt Brower). This is a case of automimicry ; the model is the same species as its mimic. Equivalent to Batesian mimicry within
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#17328524811591632-503: A man comes by chance upon a young brood [of partridges], and tries to catch them, the hen-bird rolls in front of the hunter, pretending to be lame: the man every moment thinks he is on the point of catching her, and so she draws him on and on, until every one of her brood has had time to escape; hereupon she returns to the nest and calls the young back. The behaviour is recognised as a form of mimicry by biologists. In 1823, Kirby and Spence, in their book An Introduction to Entomology , used
1768-450: A multitude of thin plated bodies, which are exceeding thin, and lie very close together, and thereby, like mother of Pearl shells, do not onely reflect a very brisk light, but tinge that light in a most curious manner; and by means of various positions, in respect of the light, they reflect back now one colour, and then another, and those most vividly. Now, that these colours are onely fantastical ones, that is, such as arise immediately from
1904-625: A paper on his theory of mimicry at a meeting of the Linnean Society of London on 21 November 1861, which was then published in 1862 as 'Contributions to an Insect Fauna of the Amazon Valley' in the society's Transactions . He elaborated on his experiences further in The Naturalist on the River Amazons . Bates put forward the hypothesis that the close resemblance between unrelated species
2040-416: A predator, such as a young bird, must attack at least one insect, say a wasp, to learn that the black and yellow colours mean a stinging insect. If bees were differently coloured, the young bird would have to attack one of them also. But when bees and wasps resemble each other, the young bird need only attack one from the whole group to learn to avoid all of them. So, fewer bees are attacked if they mimic wasps;
2176-431: A pulsating fashion. A sporocyst-sac pulsates in the snail's eye stalks, coming to resemble an irresistible meal for a songbird. In this way, it can bridge the gap between hosts, allowing it to complete its life cycle. A nematode ( Myrmeconema neotropicum ) changes the colour of the abdomen of workers of the canopy ant Cephalotes atratus to make it appear like the ripe fruits of Hyeronima alchorneoides . It also changes
2312-548: A reward. This reproductive mimicry may not be readily apparent as members of the same species may still exhibit some degree of sexual dimorphism . It is common in many species of Caricaceae . In Dodsonian mimicry, named after Calaway H. Dodson , the model belongs to a different species than the mimic. By resembling the model, a flower can lure its pollinators without offering nectar. The mechanism occurs in several orchids, including Epidendrum ibaguense which mimics flowers of Lantana camara and Asclepias curassavica , and
2448-422: A single species, it occurs when there is a palatability spectrum within a population of harmful prey. For example, monarch ( Danaus plexippus ) caterpillars feed on milkweed species of varying toxicity. Some feed on more toxic plants and store these toxins within themselves. The more palatable caterpillars thus profit from the more toxic members of the same species. Another important form of protective mimicry
2584-461: A twig or flower, they commonly do so upside down and shift their rear wings repeatedly, causing antenna-like movements of the "tails" on their wings. Studies of rear-wing damage support the hypothesis that this strategy is effective in deflecting attacks from the insect's head. Aggressive mimicry is found in predators or parasites that share some of the characteristics of a harmless species, allowing them to avoid detection by their prey or host ;
2720-399: Is Müllerian mimicry , discovered by and named after the naturalist Fritz Müller . In Müllerian mimicry, both model and mimic are aposematic, so mimicry may be mutual, does not necessarily constitute a bluff or deception and as in the wasps and bees may involve many species in a mimicry ring. In imperfect Batesian mimicry, the mimics do not exactly resemble their models. An example of this is
2856-412: Is a sheep in wolf's clothing . Mimics are less likely to be found out (for example by predators) when in low proportion to their model. Such negative frequency-dependent selection applies in most forms of mimicry. Specifically, Batesian mimicry can only be maintained if the harm caused to the predator by eating a model outweighs the benefit of eating a mimic. The nature of learning is weighted in favor of
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#17328524811592992-586: Is a combination of visual, by olfaction , and by touch. Vavilovian mimicry is found in weeds that come to share characteristics with a domesticated plant through unintentional selection . It is named after Russian botanist and geneticist Nikolai Vavilov . Selection against the weed may occur either by manually killing the weed, or by separating its seeds from those of the crop by winnowing . Vavilovian mimicry illustrates unintentional selection by man . Weeders do not want to select weeds and their seeds that look increasingly like cultivated plants, yet there
3128-441: Is a postulated form of automimicry ; where the model belongs to the same species as the mimic. This is the analogue of Batesian mimicry within a single species, and occurs when there is a palatability spectrum within a population. Examples include the monarch and the queen from the subfamily Danainae , which feed on milkweed species of varying toxicity. These species store toxins from its host plant, which are maintained even in
3264-602: Is also a stronger selective advantage for the predator to distinguish mimic from model. For this reason, mimics are usually less numerous than models, an instance of frequency-dependent selection . Some mimetic populations have evolved multiple forms ( polymorphism ), enabling them to mimic several different models and thereby to gain greater protection. Batesian mimicry is not always perfect. A variety of explanations have been proposed for this, including limitations in predators' cognition . While visual signals have attracted most study, Batesian mimicry can employ deception of any of
3400-414: Is also unclear. The model is usually another species, except in automimicry , where members of the species mimic other members, or other parts of their own bodies, and in inter-sexual mimicry, where members of one sex mimic members of the other. Many types of mimicry have been described. An overview of each follows, highlighting the similarities and differences between the various forms. Classification
3536-461: Is an evolved resemblance between an organism and another object, often an organism of another species. Mimicry may evolve between different species, or between individuals of the same species. In the simplest case, as in Batesian mimicry , a mimic resembles a model, so as to deceive a dupe, all three being of different species. A Batesian mimic, such as a hoverfly , is harmless, while its model, such as
3672-401: Is correlated with the level of toxicity of the organism. In Batesian mimicry, the mimic effectively copies the coloration of an aposematic animal, known as the model, to deceive predators into behaving as if it were distasteful. The success of this dishonest display depends on the level of toxicity of the model and the abundance of the model in the geographical area. The more toxic the model is,
3808-437: Is deceived to change its behaviour to the mimic's selective advantage. The resemblances can be via any sensory modality, including any combination of visual, acoustic, chemical, tactile, or electric. Mimicry may be to the advantage of both organisms that share a resemblance, in which case it is mutualistic ; or it can be to the detriment of one, making it parasitic or competitive . The evolutionary convergence between groups
3944-415: Is deimatic (startling) rather than aposematic as these insects are palatable to predators, so the warning colours are a bluff, not an honest signal . Some prey animals such as zebra are marked with high-contrast patterns which possibly help to confuse their predators, such as lions , during a chase. The bold stripes of a herd of running zebra have been claimed make it difficult for predators to estimate
4080-600: Is driven by the selective action of a dupe. Birds, for example, use sight to identify palatable insects, whilst avoiding noxious ones. Over time, palatable insects may evolve to resemble noxious ones, making them mimics and the noxious ones models. Models do not have to be more abundant than mimics. In the case of mutualism, each model is also a mimic; all such species can be called "co-mimics". Many harmless species such as hoverflies are Batesian mimics of strongly defended species such as wasps, while many such well-defended species form Müllerian mimicry rings of co-mimics. In
4216-401: Is inherited through the female line in so-called gentes (gens, singular). Intraspecific brood parasitism, where a female lays in a conspecific's nest, as illustrated by the goldeneye duck ( Bucephala clangula ), do not involve mimicry The parasitic butterfly Phengaris rebeli parasitizes the ant species Myrmica schencki by releasing chemicals that fool the worker ants to believe that
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4352-434: Is no other option. For example, early barnyard grass, Echinochloa oryzoides , is a weed in rice fields and looks similar to rice; its seeds are often mixed in rice and have become difficult to separate through Vavilovian mimicry. Vavilovian mimics may eventually be domesticated themselves, as in the case of rye in wheat; Vavilov called these weed-crops secondary crops . Inter-sexual mimicry (a type of automimicry, as it
4488-455: Is not such a fortuitous occasion for the mimic, and the signals it mimics tend to lower the probability of such an encounter. A case somewhat similar to Batesian mimicry is that of mimetic weeds, which imitate agricultural crops. In weed or Vavilovian mimicry , the weed survives by having seeds which winnowing machinery identifies as belonging to the crop. Vavilovian mimicry is not Batesian, because humans and crops are not enemies. By contrast,
4624-461: Is often based on function with respect to the mimic (e.g., avoiding harm). Some cases may belong to more than one class, e.g., automimicry and aggressive mimicry are not mutually exclusive, as one describes the species relationship between model and mimic, while the other describes the function for the mimic (obtaining food). The terminology used has been debated, as classifications have differed or overlapped; attempts to clarify definitions have led to
4760-451: Is often treated as synonymous with Batesian mimicry. There are many other forms however, some very similar in principle, others far separated. It is often contrasted with Müllerian mimicry , a form of mutually beneficial convergence between two or more harmful species. However, because the mimic may have a degree of protection itself, the distinction is not absolute. It can also be contrasted with functionally different forms of mimicry. Perhaps
4896-449: Is pollinated by monarch butterflies and perhaps hummingbirds . Brood parasitism or Kirbyan mimicry is a two species system where a brood parasite mimics its host. Cuckoos are a canonical example; the female cuckoo has its offspring raised by a bird of a different species, cutting down the biological mother's parental investment . The ability to lay eggs that mimic the host eggs is the key adaptation . The adaptation to different hosts
5032-493: Is red because the haem pigment needed to carry oxygen is red. Animals coloured in these ways can have striking natural patterns . Animals produce colour in both direct and indirect ways. Direct production occurs through the presence of visible coloured cells known as pigment which are particles of coloured material such as freckles. Indirect production occurs by virtue of cells known as chromatophores which are pigment-containing cells such as hair follicles. The distribution of
5168-600: Is the general appearance of an animal resulting from the reflection or emission of light from its surfaces. Some animals are brightly coloured, while others are hard to see. In some species, such as the peafowl , the male has strong patterns, conspicuous colours and is iridescent , while the female is far less visible. There are several separate reasons why animals have evolved colours. Camouflage enables an animal to remain hidden from view. Animals use colour to advertise services such as cleaning to animals of other species; to signal their sexual status to other members of
5304-508: Is the more worthy of notice since it occurs between insects both belonging to the group of butterflies which are protected by distastefulness. The explanation which applies in ordinary cases of [Batesian] mimicry—and no other has, so far as I know, been offered—cannot obtain for this imitation among protected species. Mimicry is an evolved resemblance between an organism and another object, often an organism of another species. Mimicry may evolve between different species, or between individuals of
5440-426: Is to break up what is really a continuous surface into what appears to be a number of discontinuous surfaces... which contradict the shape of the body on which they are superimposed. Animal coloration provided important early evidence for evolution by natural selection , at a time when little direct evidence was available. One of the pioneers of research into animal coloration, Edward Bagnall Poulton classified
5576-403: Is to make the animal, for example a wasp or a coral snake, highly conspicuous to potential predators, so that it is noticed, remembered, and then avoided. As Peter Forbes observes, "Human warning signs employ the same colours – red, yellow, black, and white – that nature uses to advertise dangerous creatures." Warning colours work by being associated by potential predators with something that makes
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5712-416: Is to mimic a mutualistic symbiont of the prey. Cleaner fish eat parasites and dead skin from client fish. Some allow the cleaner to venture inside their body to hunt these parasites. However, the sabre-toothed blenny or false cleanerfish ( Aspidontus taeniatus ) mimics the bluestreak cleaner wrasse ( Labroides dimidiatus ), which is recognized by other fishes as a cleaner. The false cleanerfish resembles
5848-466: Is unlike Müllerian mimicry, where the most harmful species is the model. But if a predator dies on its first encounter with a deadly snake, it has no occasion to learn to recognize the snake's warning signals. There would then be no advantage for an extremely deadly snake in being aposematic: any predator that attacked it would be killed before it could learn to avoid the deadly prey, so the snake would be better off being camouflaged to avoid attacks. But if
5984-421: Is widely accepted that mimicry evolves as a positive adaptation. The lepidopterist and novelist Vladimir Nabokov however argued that although natural selection might stabilize a "mimic" form, it would not be necessary to create it. The most widely accepted model used to explain the evolution of mimicry in butterflies is the two-step hypothesis. The first step involves mutation in modifier genes that regulate
6120-429: Is within a single species) occurs when individuals of one sex in a species mimic members of the opposite sex to facilitate sneak mating . An example is the three male forms of the marine isopod Paracerceis sculpta . Alpha males are the largest and guard a harem of females. Beta males mimic females and manage to enter the harem of females without being detected by the alpha males allowing them to mate. Gamma males are
6256-513: The Amazon rainforest . Returning home, he described multiple forms of mimicry in an 1862 paper at the Linnean Society in London, and then in his 1863 book The Naturalist on the River Amazons . The term "Batesian mimicry" has since been used in his honour, its usage becoming restricted to the situation in which a harmless mimic gains protection from its predators by resembling a distasteful model. Among
6392-467: The Arctic fox has a white coat in winter (containing little pigment), and a brown coat in summer (containing more pigment), an example of seasonal camouflage (a polyphenism ). Many animals, including mammals , birds , and amphibians , are unable to synthesize most of the pigments that colour their fur or feathers, other than the brown or black melanins that give many mammals their earth tones. For example,
6528-507: The GFP -like proteins in some corals . In some jellyfish , rhizostomins have also been hypothesized to protect against ultraviolet damage. Some frogs such as Bokermannohyla alvarengai , which basks in sunlight, lighten their skin colour when hot (and darkens when cold), making their skin reflect more heat and so avoid overheating. Some animals are coloured purely incidentally because their blood contains pigments. For example, amphibians like
6664-598: The hearing of their predators. Bats are nocturnal predators that rely on echolocation to detect their prey. Some potential prey are unpalatable to bats, and produce an ultrasonic aposematic signal, the auditory equivalent of warning coloration. In response to echolocating red bats and big brown bats , tiger moths such as Cycnia tenera produce warning sounds. Bats learn to avoid the harmful moths, but similarly avoid other species such as some pyralid moths that produce such warning sounds as well. Acoustic mimicry complexes, both Batesian and Müllerian, may be widespread in
6800-583: The olm that live in caves may be largely colorless as colour has no function in that environment, but they show some red because of the haem pigment in their red blood cells, needed to carry oxygen. They also have a little orange coloured riboflavin in their skin. Human albinos and people with fair skin have a similar colour for the same reason. Animal coloration may be the result of any combination of pigments , chromatophores , structural coloration and bioluminescence . Pigments are coloured chemicals (such as melanin ) in animal tissues. For example,
6936-451: The robber fly Mallophora bomboides , which is a Batesian mimic of its bumblebee model and prey, B. americanorum (now more commonly known as Bombus pensylvanicus ), which is noxious to predators due to its sting. Batesian mimicry stands in contrast to other forms such as aggressive mimicry , where the mimic profits from interactions with the signal receiver. One such case of this is in fireflies , where females of one species mimic
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#17328524811597072-503: The senses ; some moths mimic the ultrasound warning signals sent by unpalatable moths to bat predators, constituting auditory Batesian mimicry, while some weakly electric fish appear to mimic the electrolocation signals of strongly electric fish, probably constituting electrical mimicry. Henry Walter Bates (1825–1892) was an English explorer - naturalist who surveyed the Amazon rainforest with Alfred Russel Wallace in 1848. While Wallace returned in 1852, Bates remained for over
7208-443: The turkey vulture . It flies amongst the vultures, effectively camouflaged as a vulture which poses no threat to the hawk's prey. It hunts by suddenly breaking from the formation and ambushing its prey. Parasites can be aggressive mimics, though the situation is somewhat different from those outlined previously. They can mimic their hosts' natural prey, allowing themselves to be eaten as a pathway into their host. Leucochloridium ,
7344-462: The Continent persons are warned not to keep white pigeons, as being the most liable to destruction. Hence I can see no reason to doubt that natural selection might be most effective in giving the proper colour to each kind of grouse, and in keeping that colour, when once acquired, true and constant. Henry Walter Bates 's 1863 book The Naturalist on the River Amazons describes his extensive studies of
7480-521: The Feathers of this glorious Bird appear, through the Microscope, no less gaudy then do the whole Feathers; for, as to the naked eye 'tis evident that the stem or quill of each Feather in the tail sends out multitudes of Lateral branches, ... so each of those threads in the Microscope appears a large long body, consisting of a multitude of bright reflecting parts. ... their upper sides seem to me to consist of
7616-415: The adult. As levels of toxin vary depending on diet, some individuals are more toxic than the rest, which profit from the toxicity of those individuals, just as hoverflies benefit from mimicking well-defended wasps. One form of automimicry is where one part of an organism's body resembles another part. For example, the tails of some snakes resemble their heads; they move backwards when threatened and present
7752-435: The auditory world. The electric eel , Electrophorus , is capable of delivering a powerful electric shock that can stun or kill its prey. Bluntnose knifefishes, Brachyhypopomus , create an electric discharge pattern similar to the low voltage electrolocation discharge of the electric eel. This is thought to be Batesian mimicry of the powerfully protected electric eel. Mimicry In evolutionary biology , mimicry
7888-408: The back of the head, misleading predators into reacting as though they were the subject of an aggressive stare. Many insects have filamentous "tails" at the ends of their wings and patterns of markings on the wings themselves. These combine to create a "false head". This misdirects predators such as birds and jumping spiders . Spectacular examples occur in the hairstreak butterflies; when perching on
8024-506: The background so as to become hard to see (this covers both special and general resemblance); disruptive patterning , using colour and pattern to break up the animal's outline, which relates mainly to general resemblance; mimesis, resembling other objects of no special interest to the observer, which relates to special resemblance; countershading , using graded colour to create the illusion of flatness, which relates mainly to general resemblance; and counterillumination , producing light to match
8160-458: The background, notably in some species of squid . Countershading was first described by the American artist Abbott Handerson Thayer , a pioneer in the theory of animal coloration. Thayer observed that whereas a painter takes a flat canvas and uses coloured paint to create the illusion of solidity by painting in shadows, animals such as deer are often darkest on their backs, becoming lighter towards
8296-462: The behaviour of the ant so that the gaster (rear part) is held raised. This presumably increases the chances of the ant being eaten by birds. Reproductive mimicry occurs when the actions of the dupe directly aid in the mimic's reproduction . This is common in plants with deceptive flowers that do not provide the reward they seem to offer and it may occur in Papua New Guinea fireflies, in which
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#17328524811598432-472: The belly, creating (as zoologist Hugh Cott observed) the illusion of flatness, and against a matching background, of invisibility. Thayer's observation "Animals are painted by Nature, darkest on those parts which tend to be most lighted by the sky's light, and vice versa " is called Thayer's Law . Colour is widely used for signalling in animals as diverse as birds and shrimps. Signalling encompasses at least three purposes: Advertising coloration can signal
8568-756: The bright yellow of an American goldfinch , the startling orange of a juvenile red-spotted newt , the deep red of a cardinal and the pink of a flamingo are all produced by carotenoid pigments synthesized by plants. In the case of the flamingo, the bird eats pink shrimps, which are themselves unable to synthesize carotenoids. The shrimps derive their body colour from microscopic red algae, which like most plants are able to create their own pigments, including both carotenoids and (green) chlorophyll . Animals that eat green plants do not become green, however, as chlorophyll does not survive digestion. Chromatophores are special pigment-containing cells that may change their size, but more often retain their original size but allow
8704-570: The brilliant pink plumage of the flamingo or the roseate spoonbill was cryptic—against the momentarily pink sky at dawn or dusk. As a result, the book was mocked by critics including Theodore Roosevelt as having "pushed [the "doctrine" of concealing coloration] to such a fantastic extreme and to include such wild absurdities as to call for the application of common sense thereto." Hugh Bamford Cott 's 500-page book Adaptive Coloration in Animals , published in wartime 1940, systematically described
8840-454: The case of insects argued the case for three aspects of animal coloration that are broadly accepted today but were controversial or wholly new at the time. It strongly supported Darwin's theory of sexual selection , arguing that the obvious differences between male and female birds such as the argus pheasant were selected by the females, pointing out that bright male plumage was found only in species "which court by day". The book introduced
8976-445: The caterpillar larvae are ant larvae. This enables the larvae to be brought directly into the ant's nest. In Pouyannian mimicry, a flower mimics a female of a certain insect species, inducing the males of that species to try to copulate with the flower. This is much like aggressive mimicry in fireflies, but with a more benign outcome for the pollinator. The mechanism is named after Maurice-Alexandre Pouyanne , who first described
9112-447: The chemical energy of food. A pigment, luciferin is catalysed by the enzyme luciferase to react with oxygen, releasing light. Comb jellies such as Euplokamis are bioluminescent, creating blue and green light, especially when stressed; when disturbed, they secrete an ink which luminesces in the same colours. Since comb jellies are not very sensitive to light, their bioluminescence is unlikely to be used to signal to other members of
9248-402: The cleaner, and mimics the cleaner's "dance". Once it is allowed close to the client, it attacks, biting off a piece of its fin before fleeing. Fish wounded in this fashion soon learn to distinguish mimic from model, but because the similarity is close they also become much more cautious of the model. A mechanism that does not involve any luring is seen in the zone-tailed hawk , which resembles
9384-571: The colour of the stones adjacent to it; it does so also when alarmed. Cephalopod molluscs like squid can voluntarily change their coloration by contracting or relaxationg small muscles around their chromatophores. The energy cost of the complete activation of the chromatophore system is very high, equalling nearly as much as all the energy used by an octopus at rest. Amphibians such as frogs have three kinds of star-shaped chromatophore cells in separate layers of their skin. The top layer contains ' xanthophores ' with orange, red, or yellow pigments;
9520-484: The colours and effects they need. Animal coloration has been a topic of interest and research in biology for centuries. In the classical era , Aristotle recorded that the octopus was able to change its coloration to match its background, and when it was alarmed. In his 1665 book Micrographia , Robert Hooke describes the "fantastical" ( structural , not pigment) colours of the Peacock's feathers: The parts of
9656-576: The concept of frequency-dependent selection , as when edible mimics are less frequent than the distasteful models whose colours and patterns they copy. In the book, Poulton also coined the term aposematism for warning coloration, which he identified in widely differing animal groups including mammals (such as the skunk ), bees and wasps, beetles, and butterflies. Frank Evers Beddard 's 1892 book, Animal Coloration , acknowledged that natural selection existed but examined its application to camouflage, mimicry and sexual selection very critically. The book
9792-402: The evolution of wasp-like appearance, it has been argued that insects evolve to masquerade wasps since predatory wasps do not attack each other, and that this mimetic resemblance has had the useful side-effect of deterring vertebrate predators. Mimicry can result in an evolutionary arms race if mimicry negatively affects the model, in which case the model can evolve a different appearance from
9928-442: The extreme, sexual selection may drive species to extinction, as has been argued for the enormous horns of the male Irish elk, which may have made it difficult for mature males to move and feed. Different forms of sexual selection are possible, including rivalry among males, and selection of females by males. Warning coloration (aposematism) is effectively the "opposite" of camouflage, and a special case of advertising. Its function
10064-435: The first mathematical model of mimicry for this phenomenon: if a common predator confuses the two species, individuals in both those species are more likely to survive, as fewer individuals of either species are killed by the predator. The term Müllerian mimicry , named in his honour, has since been used for this mutualistic form of mimicry. Müller wrote that The resemblance of the genera named [ Ituna and Thyridia ]
10200-562: The fly Spilomyia longicornis , which mimics vespid wasps. However, it is not a perfect mimic. Wasps have long black antennae and this fly does not. Instead, they wave their front legs above their heads to look like the antennae on the wasps. Many reasons have been suggested for imperfect mimicry. Imperfect mimics may simply be evolving towards perfection. They may gain advantage from resembling multiple models at once. Humans may evaluate mimics differently from actual predators. Mimics may confuse predators by resembling both model and nonmimic at
10336-423: The forms of protective coloration, in a way which is still helpful. He described: protective resemblance; aggressive resemblance; adventitious protection; and variable protective resemblance. These are covered in turn below. Protective resemblance is used by prey to avoid predation. It includes special protective resemblance, now called mimesis , where the whole animal looks like some other object, for example when
10472-634: The genus Thaumoctopus (the mimic octopus ) are able to intentionally alter their body shape and coloration to resemble dangerous sea snakes or lionfish . In the Amazon, the helmeted woodpecker ( Dryocopus galeatus ), a rare species which lives in the Atlantic Forest of Brazil, Paraguay, and Argentina, has a similar red crest, black back, and barred underside to two larger woodpeckers: Dryocopus lineatus and Campephilus robustus . This mimicry reduces attacks on D. galeatus . Batesian mimicry occurs in
10608-470: The insects in the Amazon basin, and especially the butterflies. He discovered that apparently similar butterflies often belonged to different families, with a harmless species mimicking a poisonous or bitter-tasting species to reduce its chance of being attacked by a predator, in the process now called after him, Batesian mimicry . Edward Bagnall Poulton 's strongly Darwinian 1890 book The Colours of Animals, their meaning and use, especially considered in
10744-437: The likelihood of encountering one. However, in areas where the model is scarce or locally extinct, mimics are driven to accurate aposematic coloration. This is because predators attack imperfect mimics more readily where there is little chance that they are the model species. Frequency-dependent selection may also have driven Batesian mimics to become polymorphic in rare cases where a single genetic switch controls appearance, as in
10880-411: The males of some species, such as birds-of-paradise, were very different from the females. Darwin explained such male-female differences in his theory of sexual selection in his book The Descent of Man . Once the females begin to select males according to any particular characteristic, such as a long tail or a coloured crest, that characteristic is emphasized more and more in the males. Eventually all
11016-429: The males will have the characteristics that the females are sexually selecting for, as only those males can reproduce. This mechanism is powerful enough to create features that are strongly disadvantageous to the males in other ways. For example, some male birds-of-paradise have wing or tail streamers that are so long that they impede flight, while their brilliant colours may make the males more vulnerable to predators. In
11152-400: The mating signals of another species, deceiving males to come close enough for them to eat. Mimicry sometimes does not involve a predator at all though. Such is the case in dispersal mimicry , where the mimic once again benefits from the encounter. For instance, some fungi have their spores dispersed by insects by smelling like carrion . In protective mimicry, the meeting between mimic and dupe
11288-447: The mating signals of females of the genus Photinus . Male fireflies from several different genera are attracted to these " femmes fatales ", and are captured and eaten. Each female has a repertoire of signals matching the delay and duration of the flashes of the female of the corresponding species. Some carnivorous plants may be able to increase their rate of capturing insect prey through mimicry. A different aggressive strategy
11424-421: The middle layer contains ' iridophores ' with a silvery light-reflecting pigment; while the bottom layer contains ' melanophores ' with dark melanin. While many animals are unable to synthesize carotenoid pigments to create red and yellow surfaces, the green and blue colours of bird feathers and insect carapaces are usually not produced by pigments at all, but by structural coloration. Structural coloration means
11560-417: The milk snakes and the deadly coral snakes are mimics, while the false coral snakes are the model. In Wasmannian mimicry , the mimic resembles a model that it lives along with in a nest or colony. Most of the models here are eusocial insects, principally ants. Gilbertian mimicry is bipolar, involving only two species. The potential host (or prey) drives away its parasite (or predator) by mimicking it,
11696-415: The mimic and the model benefit from the interaction, which could thus be classified as mutualism . The signal receiver also benefits by this system, despite being deceived about species identity, as it is able to generalize the pattern to potentially harmful encounters. The distinction between mimic and model that is clear in Batesian mimicry is also blurred. Where one species is scarce and another abundant,
11832-410: The mimic is sufficiently protected. Convergent evolution is an alternative explanation for why coral reef fish have come to resemble each other; the same applies to benthic marine invertebrates such as sponges and nudibranchs . In its broadest definition, mimicry can include non-living models. The specific terms masquerade and mimesis are sometimes used when the models are inanimate, and
11968-521: The mimic. Mimics may have different models for different life cycle stages, or they may be polymorphic , with different individuals imitating different models, as occurs in Heliconius butterflies. Models tend to be relatively closely related to their mimics, but mimicry can be of vastly different species, for example when spiders mimic ants. Most known mimics are insects, though many other examples including vertebrates , plants, and fungi exist. It
12104-402: The mimicked species must have warning coloration, because appearing to be bitter-tasting or dangerous gives natural selection something to work on. Once a species has a slight, chance, resemblance to a warning coloured species, natural selection can drive its colours and patterns towards more perfect mimicry. There are numerous possible mechanisms, of which the best known are: Batesian mimicry
12240-465: The mimicry is again bipolar. In automimicry , another bipolar system, model and mimic are the same, as when blue lycaenid butterflies have 'tails' or eyespots on their wings that mimic their own heads, misdirecting predator dupes to strike harmlessly. Many other types of mimicry exist. Use of the word mimicry dates to 1637. It derives from the Greek term mimetikos , "imitative", in turn from mimetos ,
12376-400: The mimicry's purpose is crypsis . For example, animals such as flower mantises , planthoppers , comma and geometer moth caterpillars resemble twigs, bark, leaves, bird droppings or flowers. Many animals bear eyespots , which are hypothesized to resemble the eyes of larger animals. They may not resemble any specific organism's eyes, and whether or not animals respond to them as eyes
12512-425: The mimics, for a predator that has a bad first experience with a model tends to avoid anything that looks like it for a long time, and does not re-sample soon to see whether the initial experience was a false negative. However, if mimics become more abundant than models, then the probability of a young predator having a first experience with a mimic increases. Batesian systems are therefore most likely to be stable where
12648-614: The model Micrurus fulvius showed that color proportions in these snakes were important in deceiving predators but that the order of the colored rings was not. Batesian mimicry of ants appears to have evolved in certain plants, as a visual anti-herbivory strategy , analogous to a herbivorous insect's mimicking a well-defended insect to deter predators. Passiflora flowers of at least 22 species, such as P. incarnata , have dark dots and stripes on their flowers thought to serve this purpose. Predators may identify their prey by sound as well as sight; mimics have accordingly evolved to deceive
12784-493: The model and the dupe are the same; this occurs for example in aggressive mimicry , where a predator in wolf-in-sheep's-clothing style resembles its prey, allowing it to hunt undetected. Mimicry is not limited to animals; in Pouyannian mimicry , an orchid flower is the mimic, resembling a female bee, its model; the dupe is the male bee of the same species, which tries to copulate with the flower, enabling it to transfer pollen, so
12920-418: The model is more abundant than the mimic. There are many Batesian mimics among butterflies and moths . Consul fabius and Eresia eunice imitate unpalatable Heliconius butterflies such as H. ismenius . Limenitis arthemis imitate the poisonous pipevine swallowtail ( Battus philenor ). Several palatable moths produce ultrasonic click calls to mimic unpalatable tiger moths. Octopuses of
13056-499: The model is variously known as the [signal] receiver , dupe or operator . By parasitising the honest warning signal of the model, the Batesian mimic gains an advantage, without having to go to the expense of arming itself. The model, on the other hand, is disadvantaged, along with the dupe. If impostors appear in high numbers, positive experiences with the mimic may result in the model being treated as harmless. At higher frequency there
13192-429: The more likely it is that the predator will avoid the mimic. The abundance of the model species is also important for the success of the mimic because of frequency-dependent selection . When the model is abundant, mimics with imperfect model patterns or slightly different coloration from the model are still avoided by predators. This is because the predator has a strong incentive to avoid potentially lethal organisms, given
13328-571: The observations in Bates's 1862 paper is the statement: I was never able to distinguish the Leptalides from the species they imitated, although they belong to a family totally different in structure and metamorphosis from the Heliconidae , without examining them closely after capture. The German naturalist Fritz Müller also spent many years studying butterflies in the Amazon rainforest. He first published
13464-411: The partial replacement of old terms with new ones. Mimicry is defensive or protective when organisms are able to avoid harmful encounters by deceiving enemies into treating them as something else. In Batesian mimicry, the mimic resembles the model, but does not have the attribute that makes it unprofitable to predators (e.g., unpalatability, or the ability to sting). In other words, a Batesian mimic
13600-400: The pattern seen in many flowers known as nectar guides . Spiders change their web day to day, which can be explained by the ability of bees to remember web patterns. Another case is where males are lured towards what seems to be a sexually receptive female. The model in this situation is the same species as the dupe. Female fireflies of the genus Photuris emit light signals that mimic
13736-424: The phenomenon. It is most common in orchids, which mimic females of the order Hymenoptera (generally bees and wasps), and may account for around 60% of pollinations. Depending on the morphology of the flower, a pollen sac called a pollinium is attached to the head or abdomen of the male. This is then transferred to the stigma of the next flower the male tries to inseminate, resulting in pollination. The mimicry
13872-723: The pigment particles in the chromatophores can change under hormonal or neuronal control. For fishes it has been demonstrated that chromatophores may respond directly to environmental stimuli like visible light, UV-radiation, temperature, pH, chemicals, etc. colour change helps individuals in becoming more or less visible and is important in agonistic displays and in camouflage. Some animals, including many butterflies and birds, have microscopic structures in scales, bristles or feathers which give them brilliant iridescent colours. Other animals including squid and some deep-sea fish can produce light , sometimes of different colours. Animals often use two or more of these mechanisms together to produce
14008-632: The pigment within them to become redistributed, thus varying the colour and pattern of the animal. Chromatophores may respond to hormonal and/or neurobal control mechanisms, but direst responses to stimulation by visible light, UV-radiation, temperature, pH-changes, chemicals, etc. have also been documented. The voluntary control of chromatophores is known as metachrosis. For example, cuttlefish and chameleons can rapidly change their appearance, both for camouflage and for signalling, as Aristotle first noted over 2000 years ago: The octopus ... seeks its prey by so changing its colour as to render it like
14144-456: The plant kingdom, where the chameleon vine adapts its leaf shape and colour to match that of the plant it is climbing. In Müllerian mimicry, two or more species have similar warning or aposematic signals and both share genuine anti-predation attributes (e.g. being unpalatable), as first described in Heliconius butterflies. This type of mimicry is unique in several respects. Firstly, both
14280-505: The point of hatching. The butterflies avoid laying eggs near existing ones, reducing intraspecific competition between caterpillars, which are also cannibalistic , so those that lay on vacant leaves provide their offspring with a greater chance of survival. The stipules thus appear to have evolved as Gilbertian mimics of butterfly eggs, under selection pressure from these caterpillars. Browerian mimicry, named after Lincoln P. Brower and Jane Van Zandt Brower who first described it in 1967,
14416-488: The predator adapts to become more efficient at defeating the prey's adaptations. Some organisms have evolved to make detection less likely, for example by nocturnality and camouflage . Others have developed chemical defences such as the deadly toxins of certain snakes and wasps, or the noxious scent of the skunk . Such prey often send clear and honest warning signals to their attackers with conspicuous aposematic (warning) patterns. The brightness of such warning signs
14552-408: The predator first learnt to avoid a less deadly warning-coloured snake, the deadly species could profit by mimicking the less dangerous snake. Some harmless milk snakes ( Lampropeltis triangulum ), the moderately toxic false coral snakes ( Erythrolamprus aesculapii ), and the deadly coral snakes ( Micrurus ) all have a red background color with black and white/yellow rings. In this system, both
14688-435: The predator with the tail, improving their chances of escape without fatal harm. Some fishes have eyespots near their tails, and when mildly alarmed swim slowly backwards, presenting the tail as a head. Some insects such as some lycaenid butterflies have tail patterns and appendages of various degrees of sophistication that promote attacks at the rear rather than at the head. Several species of pygmy owl bear "false eyes" on
14824-665: The prey's speed and direction accurately, or to identify individual animals, giving the prey an improved chance of escape. Since dazzle patterns (such as the zebra's stripes) make animals harder to catch when moving, but easier to detect when stationary, there is an evolutionary trade-off between dazzle and camouflage . There is evidence that the zebra's stripes could provide some protection from flies and biting insects. Many animals have dark pigments such as melanin in their skin , eyes and fur to protect themselves against sunburn (damage to living tissues caused by ultraviolet light). Another example of photoprotective pigments are
14960-412: The principles of camouflage and mimicry. The book contains hundreds of examples, over a hundred photographs and Cott's own accurate and artistic drawings, and 27 pages of references. Cott focussed especially on "maximum disruptive contrast", the kind of patterning used in military camouflage such as disruptive pattern material . Indeed, Cott describes such applications: the effect of a disruptive pattern
15096-437: The production of colour by microscopically-structured surfaces fine enough to interfere with visible light , sometimes in combination with pigments: for example, peacock tail feathers are pigmented brown, but their structure makes them appear blue, turquoise and green. Structural coloration can produce the most brilliant colours, often iridescent . For example, the blue/green gloss on the plumage of birds such as ducks , and
15232-418: The purple/blue/green/red colours of many beetles and butterflies are created by structural coloration. Animals use several methods to produce structural colour, as described in the table. Bioluminescence is the production of light , such as by the photophores of marine animals, and the tails of glow-worms and fireflies . Bioluminescence, like other forms of metabolism , releases energy derived from
15368-435: The rare species can be said to be the mimic. When both are present in similar numbers, however, it makes more sense to speak of each as a co-mimic than of distinct 'mimic' and 'model' species, as their warning signals tend to converge. Also, the mimetic species may exist on a continuum from harmless to highly noxious, so Batesian mimicry grades smoothly into Müllerian convergence. Emsleyan or Mertensian mimicry describes
15504-509: The recent account of evolution by Wallace and Charles Darwin , as outlined in his famous 1859 book The Origin of Species . Because the Darwinian explanation required no supernatural forces, it met with considerable criticism from anti-evolutionists , both in academic circles and in the broader social realm . Most living things have predators and therefore are in a constant evolutionary arms race to develop antipredator adaptations , while
15640-432: The refractions of the light, I found by this, that water wetting these colour'd parts, destroy'd their colours, which seem'd to proceed from the alteration of the reflection and refraction. According to Charles Darwin 's 1859 theory of natural selection , features such as coloration evolved by providing individual animals with a reproductive advantage. For example, individuals with slightly better camouflage than others of
15776-456: The reverse of host-parasite aggressive mimicry. It was coined by Pasteur as a phrase for such rare mimicry systems, and is named after the American ecologist Lawrence E. Gilbert who described it in 1975. The classical instance of Gilbertian mimicry is in the plant genus Passiflora , which is grazed by the micropredator larvae of some Heliconius butterflies. The host plants have evolved stipules that mimic mature Heliconius eggs near
15912-630: The same species would, on average, leave more offspring. In his Origin of Species , Darwin wrote: When we see leaf-eating insects green, and bark-feeders mottled-grey; the alpine ptarmigan white in winter, the red-grouse the colour of heather, and the black-grouse that of peaty earth, we must believe that these tints are of service to these birds and insects in preserving them from danger. Grouse, if not destroyed at some period of their lives, would increase in countless numbers; they are known to suffer largely from birds of prey; and hawks are guided by eyesight to their prey, so much so, that on parts of
16048-445: The same applies to wasps that mimic bees. The result is mutual resemblance for mutual protection. Some animals such as many moths , mantises and grasshoppers , have a repertoire of threatening or startling behaviour , such as suddenly displaying conspicuous eyespots or patches of bright and contrasting colours, so as to scare off or momentarily distract a predator. This gives the prey animal an opportunity to escape. The behaviour
16184-403: The same species (e.g. to attract mates or repel rivals); more likely, the light helps to distract predators or parasites. Some species of squid have light-producing organs ( photophores ) scattered all over their undersides that create a sparkling glow. This provides counter-illumination camouflage, preventing the animal from appearing as a dark shape when seen from below. Some anglerfish of
16320-436: The same species. Often, mimicry functions to protect from predators . Mimicry systems have three basic roles: a mimic, a model, and a dupe. When these correspond to three separate species, the system is called disjunct; when the roles are taken by just two species, the system is called bipolar. Mimicry evolves if a dupe (such as a predator) perceives a mimic (such as a palatable prey) as a model (the organism it resembles), and
16456-533: The same species; and in mimicry , taking advantage of the warning coloration of another species. Some animals use flashes of colour to divert attacks by startling predators. Zebras may possibly use motion dazzle, confusing a predator's attack by moving a bold pattern rapidly. Some animals are coloured for physical protection, with pigments in the skin to protect against sunburn, while some frogs can lighten or darken their skin for temperature regulation . Finally, animals can be coloured incidentally. For example, blood
16592-428: The same time (satyric mimicry). Kin selection may enforce poor mimicry. The selective advantage of better mimicry may not outweigh the advantages of other strategies like thermoregulation or camouflage. Only certain traits may be required to deceive predators; for example, tests on the sympatry / allopatry border (where the two are in the same area, and where they are not) of the mimic Lampropeltis elapsoides and
16728-461: The services an animal offers to other animals. These may be of the same species, as in sexual selection , or of different species, as in cleaning symbiosis . Signals, which often combine colour and movement, may be understood by many different species; for example, the cleaning stations of the banded coral shrimp Stenopus hispidus are visited by different species of fish, and even by reptiles such as hawksbill sea turtles . Darwin observed that
16864-401: The sharpest contrast here is with aggressive mimicry where a predator or parasite mimics a harmless species, avoiding detection and improving its foraging success. The imitating species is called the mimic , while the imitated species (protected by its toxicity, foul taste or other defenses) is known as the model . The predatory species mediating indirect interactions between the mimic and
17000-468: The signal of Pteroptyx effulgens is used by P. tarsalis to form aggregations to attract females. Other forms of mimicry have a reproductive component, such as Vavilovian mimicry involving seeds, vocal mimicry in birds, and aggressive and Batesian mimicry in brood parasite-host systems. Bakerian mimicry, named after Herbert G. Baker , is a form of automimicry where female flowers mimic male flowers of their own species, cheating pollinators out of
17136-650: The smallest males and mimic juveniles. This also allows them to mate with the females without the alpha males detecting them. Similarly, among common side-blotched lizards , some males mimic the yellow throat coloration and even mating rejection behaviour of the other sex to sneak matings with guarded females. These males look and behave like unreceptive females. This strategy is effective against "usurper" males with orange throats, but ineffective against blue throated "guarder" males, which chase them away. Female spotted hyenas have pseudo-penises that make them look like males. Animal coloration Animal colouration
17272-450: The strategy resembles a wolf in sheep's clothing , though no conscious deceptive intent is involved. The mimic may resemble the prey or host itself, or another organism that does not threaten the prey or host. Several spiders use aggressive mimicry to lure prey. Species such as the silver argiope ( Argiope argentata ) employ prominent patterns in the middle of their webs, such as zigzags. These may reflect ultraviolet light, and mimic
17408-509: The swallowtail butterflies (the Papilionidae ) such as the pipevine swallowtail , and in the New Zealand stonefly Zelandoperla fenestrata . Batesian mimicry is a case of protective or defensive mimicry , where the mimic does best by avoiding confrontations with the signal receiver. It is a disjunct system, which means that all three parties are from different species. An example would be
17544-473: The term "mimicry" informally to depict the way that the structure and coloration of some insects resembled objects in their environments: A jumping bug, very similar to the one figured by Schellenberg , also much resembles the lichens of the oak on which I took it. The spectre tribe ( Phasma ) go still further in this mimicry, representing a small branch with its spray. The English naturalist Henry Walter Bates worked for several years on butterflies in
17680-508: The unusual case where a deadly prey mimics a less dangerous species. It was first proposed by M. G. Emsley in 1966 as a possible explanation for how a predator can learn to avoid a very dangerous aposematic animal, such as a coral snake , when the predator is very likely to die, making learning unlikely. The theory was developed by the German biologist Wolfgang Wickler who named it after the German herpetologist Robert Mertens . The scenario
17816-412: The verbal adjective of mimeisthai , "to imitate". "Mimicry" was first used in zoology by the English entomologists William Kirby and William Spence in 1823. Originally used to describe people, "mimetic" was used in zoology from 1851. Aristotle wrote in his History of Animals that partridges use a deceptive distraction display to lure predators away from their flightless young: When
17952-658: The warning coloured animal unpleasant or dangerous. This can be achieved in several ways, by being any combination of: Warning coloration can succeed either through inborn behaviour ( instinct ) on the part of potential predators, or through a learned avoidance. Either can lead to various forms of mimicry. Experiments show that avoidance is learned in birds , mammals , lizards , and amphibians , but that some birds such as great tits have inborn avoidance of certain colours and patterns such as black and yellow stripes. Mimicry means that one species of animal resembles another species closely enough to deceive predators. To evolve,
18088-480: Was an antipredator adaptation . He noted that some species showed very striking coloration and flew in a leisurely manner, almost as if taunting predators to eat them. He reasoned that these butterflies were unpalatable to birds and other insectivores , and were thus avoided by them. He extended that logic to forms that closely resembled such protected species and mimicked their warning coloration but not their toxicity. This naturalistic explanation fitted well with
18224-439: Was first described by the pioneering naturalist Fritz Müller . When a distasteful animal comes to resemble a more common distasteful animal, natural selection favours individuals that even very slightly better resemble the target. For example, many species of stinging wasp and bee are similarly coloured black and yellow. Müller's explanation of the mechanism for this was one of the first uses of mathematics in biology. He argued that
18360-559: Was first described by the pioneering naturalist Henry W. Bates . When an edible prey animal comes to resemble, even slightly, a distasteful animal, natural selection favours those individuals that even very slightly better resemble the distasteful species. This is because even a small degree of protection reduces predation and increases the chance that an individual mimic will survive and reproduce. For example, many species of hoverfly are coloured black and yellow like bees, and are in consequence avoided by birds (and people). Müllerian mimicry
18496-568: Was in turn roundly criticised by Poulton. Abbott Handerson Thayer 's 1909 book Concealing-Coloration in the Animal Kingdom , completed by his son Gerald H. Thayer, argued correctly for the widespread use of crypsis among animals, and in particular described and explained countershading for the first time. However, the Thayers spoilt their case by arguing that camouflage was the sole purpose of animal coloration, which led them to claim that even
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